LEOMINSTER -- Local residents who find lady bugs in their homes may want to reconsider tolerating their presence, as pest experts warn they are a foreign breed and are considered a nuisance indoors.

The Asian lady beetle first came into the area in the late 20th century and is often mistaken for the seven-spotted ladybug, which is officially designated as the Massachusetts state insect.

Both are members of the coccinellidae family of insects and eat the aphids that destroy leaves and crops. Asian lady beetles have black spots and vary in color from red to orange to tan.

"They are a mixed blessing," said Joanne DiNardo, conservation agent for the city of Leominster.

While Asian lady beetles join their native cousins in protecting plants like the apple trees at Sholan Farms, DiNardo said they also enter the walls of people's homes in the winter and emerge in the spring.

"They're following their natural instincts," said Neil Zanni, owner of The Gardeners' Spot in Leominster.

He said the insects come from a warmer climate and traditionally burrow into the bark of trees to wait out the cold months. In this region, they seek out the cracks around doors and windows. Once the weather warms up, they often end up going inside the building.

Craig S. Hollingsworth, entomologist with the UMass Amherst extension, said Asian lady beetles do not reproduce inside the walls of people's homes, and the ones that crawl out are the same ones that crawled in.

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"They're not spreading diseases, they're not a health problem; they're a nuisance," said Hollingsworth. He said they do not demolish structures like carpenter ants or chew on clothing like moths but can stain fabrics, walls and furniture.

Hollingsworth said this comes from one of two reflexes they have when disturbed. One reaction they show is to immobilize themselves, tuck their legs and wings in and fall to the ground. The other is to bleed from their leg joints.

The Asian lady beetles have a foul-smelling substance called hemolymph in place of blood that they can spray.

"The blood tends to be smelly, sticky. It's a deterrent to predators," said Hollingsworth. The substance also comes out if the Asian lady beetles are squished.

Karen Lacovelli, 60, of Sterling, knows this firsthand. She's seen them for years and said they always leave a mess when crushed.

"All my walls are a white color, and a yellowish stain doesn't set well with me," she said. She said they were in especially large numbers this winter and came out when it was sunny.

Hollingsworth recommends picking them up with a vacuum cleaner or sweeping them up to avoid making a mess. He gets them in his house and said if many of them congregate at a window he will open it to let them out.

Hollingsworth said he's been having an average year of them and said he does not have any data on any growth in population. He said they can be found all over the nation.

In the 1960s, the U.S. Department of Agriculture started importing the Asian lady beetles to both coasts of America to eat pests that threatened pecans, apples and other crops, according to a report from the University of Kentucky Cooperative Extension Service. It is not known if the wild population of insects are descendants of those populations or stowaways from imported Asian produce.

Zanni said the population is expected to increase for about two more decades because there are so many aphids for the beetles to eat. He said they are not a threat to native ladybugs because there is plenty of food to go around for both of them.

"There's no way to stop them," said Zanni. "They've been here a long time."

Scott Wheeler, service coordinator at Bain Pest Control Services in Lowell, said the Asian lady beetles are a "beneficial pest" and people have mixed feelings about killing them because they protect plants, orchards and gardens.

He also recommended vacuuming them once they get inside but said the best way to avoid them is to caulk gaps around windows and doors.

In other parts of the world labybugs are called "ladybirds" because beetles are not in the hemiptera order and therefore are not considered true bugs. The Asian lady beetle has a lifespan of about three years.

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